Hello All,
I am finding it really hard to perform write and read operations on the EEPROM connected to the MCU by two wires using the I2C Protocol.
I've read the data sheets, written the code exactly matching the datasheet info, but it was of no avail.
Please help me out.
My code looks something like this
void Write_Start(void) { E2P_SDA = 1; E2P_SCL = 1; delay_i2c(); E2P_SDA = 0; delay_i2c(); E2P_SCL = 0; delay_i2c(); } void Write_to_E2P(void) { unsigned char DEV_SEL_CODE = 0x0A0; unsigned char ADDR_MSB = 0x50; unsigned char ADDR_LSB = 0x05; unsigned char i; Write_Start(); for(i=7;i>=0;i--) { E2P_SDA = DEV_SEL_CODE^i; E2P_SCL = 0; delay_i2c(); E2P_SCL = 1; delay_i2c(); } E2P_SDA = 1; E2P_SCL = 0; delay_i2c(); E2P_SCL = 1; delay_i2c(); delay_i2c(); E2P_SCL = 0; delay_i2c(); if(E2P_SDA == 0) LED1=1; for(i=7;i>=0;i--) { E2P_SDA = ADDR_MSB^i; E2P_SCL = 0; delay_i2c(); E2P_SCL = 1; delay_i2c(); } E2P_SDA = 1; E2P_SCL = 0; delay_i2c(); E2P_SCL = 1; delay_i2c(); delay_i2c(); E2P_SCL = 0; delay_i2c(); if(E2P_SDA == 0) LED2=1; for(i=7;i>=0;i--) { E2P_SDA = ADDR_LSB^i; E2P_SCL = 0; delay_i2c(); E2P_SCL = 1; delay_i2c(); } E2P_SDA = 1; E2P_SCL = 0; delay_i2c(); E2P_SCL = 1; delay_i2c(); delay_i2c(); E2P_SCL = 0; delay_i2c(); if(E2P_SDA == 0) LED3=1; for(i=7;i>=0;i--) { E2P_SDA = current_channel^i; E2P_SCL = 0; delay_i2c(); E2P_SCL = 1; delay_i2c(); } E2P_SDA = 1; E2P_SCL = 0; delay_i2c(); E2P_SCL = 1; delay_i2c(); delay_i2c(); E2P_SCL = 0; delay_i2c(); if(E2P_SDA == 0) LED4=1; }
have you verified timing using a scope? are you sure the data line is not held low (hence occupying the bus)...?
i have not tested it with a scope. will the eeprom occupy the bus in the 9th clock period, if the byte is not written , will it not release the bus ? Can you please go through the code and tell me if my understanding of the protocol is indeed right ?
If you are already into bit banging, maybe it is better to take a modular approach: write a small routine that places a start on the bus. Then do the same for stop, ack, nack, a byte etc. It is hard to say what's wrong without snooping the bus.
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So help out: Write a FAQ listing the regulars, togeter with a quick list of their level of ignorance and their most important delusions.
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